1. Field of the Invention
The present invention relates to a nitride semiconductor element such as a light-emitting device including a nitride semiconductor light-emitting diode element, a nitride semiconductor laser element and the like and an electronic device including a nitride semiconductor transistor element and the like; a method for manufacturing the nitride semiconductor element; a method for manufacturing a nitride semiconductor layer; and a nitride semiconductor light-emitting element.
2. Description of the Background Art
Conventionally, a GaN substrate, an SiC substrate, a sapphire substrate, and the like are used as a substrate used for a nitride semiconductor element. From the viewpoint of improving mass productivity of the nitride semiconductor element while allowing a decrease in manufacturing cost, a sapphire substrate is often used.
However, when a nitride semiconductor element is fabricated by stacking a nitride semiconductor layer on the sapphire substrate, dislocation (threading dislocation) propagating through the nitride semiconductor layer forming a nitride semiconductor element in its thickness direction may occur due to a high lattice mismatch ratio between the sapphire substrate and the nitride semiconductor layer.
The above-described threading dislocation leads to deterioration in characteristics of various nitride semiconductor elements such as a decrease in light emission efficiency in the nitride semiconductor light-emitting diode element, a shortened lifespan of the nitride semiconductor laser element, and reduction in electron mobility in the nitride semiconductor transistor element.
Thus, for example, Patent Document 1 (Japanese Patent Laying-Open No. 2002-043233) discloses that a GaN semiconductor layer is stacked on a sapphire substrate, an SiN layer provided with a plurality of openings is stacked on the GaN semiconductor layer, and a GaN semiconductor layer is further stacked on the SiN layer, thereby decreasing the dislocation density in the GaN semiconductor layer corresponding to the topmost layer, to allow improvement in crystallinity.